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First published online December 10, 2003
Journal of Experimental Biology 207, 233-248 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00763

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Locomotion of lizards on inclines and perches: hindlimb kinematics of an arboreal specialist and a terrestrial generalist

Timothy E. Higham^* and Bruce C. Jayne

Department of Biological Sciences, University of Cincinnati, PO Box 210006, Cincinnati, OH 45221-0006, USA

View larger version (40K): [in a new window]   Fig. 1. Lateral and dorsal views of Chamaeleo calyptratus moving on a level perch including (A) footfall (0 ms), (B) midstance (488 ms), (C) endstance (972 ms) and (D) midswing (1240 ms). The lizard is moving at approximately 17 cm s-1.

View larger version (10K): [in a new window]   Fig. 2. Schematic figures of the right hindlimb for a single complete stride for C. calyptratus (A) and D. dorsalis (B) moving on a level treadmill. The five figures for each animal indicate (from left to right) footfall, midstance, endstance, midswing and the subsequent footfall. The red, blue, yellow and green portions are the femur, tibia, metatarsal and toe, respectively. Both of the strides are to the same scale.

View larger version (18K): [in a new window]   Fig. 3. Mean values of y and z of the right hindlimb relative to the hip (y=0, z=0) for each combination of species (rows; A-D, C. calyptratus; E,F, D. dorsalis), surface (rows; A,B, 2.4 cm perch; C-F, treadmill), and incline (columns; -30°, 0°, 30°). From proximal to distal the endpoints of the line segments represent the hip, knee, ankle, distal end of the metatarsala and tip of the toe. Sample sizes range from 14 to 16 strides (from four individuals per species) for each combination of the three factors. The projection onto the y-z plane corresponds to an anterior view. With the exception of downhill locomotion on the treadmill at footfall, the femur of D. dorsalis is more erect than that of C. calyptratus.

View larger version (27K): [in a new window]   Fig. 4. Angles of the knee joint, femur retraction, femur rotation and femur depression versus time (as a percentage of stride cycle) for a single stride for C. calyptratus (A) and D. dorsalis (B) moving on a level treadmill. The arrows indicate the end of stance, and footfall occurs at time 0%. The speeds for C. calyptratus and D. dorsalis were approximately 17 cm s-1 and 50 cm s-1, respectively.

View larger version (35K): [in a new window]   Fig. 5. Dorsal (A-C) and lateral (D-F) views of paths moved by different parts of the hindlimb relative to the hip (0, 0, 0) for C. calyptratus moving on a level perch (A,D) and a level treadmill (B,E) and D. dorsalis (C,F) moving on a level treadmill. Anterior is towards to the right of each plot. The closed and open symbols indicate the swing and stance phases, respectively. The overall direction of movement in the loops is clockwise.

View larger version (16K): [in a new window]   Fig. 6. Mean values of (A) relative stride length (open symbols) and step length (filled symbols), (B) relative minimum (filled symbols) and maximum (open symbols) hip height (Yhip), (C) relative longitudinal position of the ankle (Xankle) and (D) relative lateral position of the ankle (Zankle). Circles and triangles represent C. calyptratus on the treadmill and perch, respectively. Squares represent D. dorsalis on the treadmill. Tables 1, 2 and 4 summarize the results of the statistical comparisons among species, inclines and surfaces.

View larger version (18K): [in a new window]   Fig. 7. Mean values of the femur angles of C. calyptratus on the perch (triangles) and treadmill (circle) and D. dorsalis on the treadmill (squares). Values include minimum (filled symbols) and maximum (open symbols) long-axis femur rotation (A), femur depression (B), and femur retraction (C). Table 3 summarizes the statistical comparisons among species, inclines and surfaces.

View larger version (16K): [in a new window]   Fig. 8. Mean values of the two-dimensional angle of pelvic rotation (A), and the three-dimensional angles of knee angle at footfall (B) and ankle angle at footfall (C). Circles and triangles represent C. calyptratus on the treadmill and perch, respectively. Squares represent D. dorsalis on the treadmill. Table 3 summarizes the statistical comparisons among species, inclines and surfaces.

View larger version (12K): [in a new window]   Fig. 9. (A) Discriminant function 1 (DF1) versus discriminant function 2 (DF2) and (B) DF1 versus discriminant function 3 (DF3), from an analysis of 15 kinematic variables for C. calyptratus moving on a perch (filled symbols) and a treadmill (open symbols). Each point is for an individual stride. Table 5 provides the canonical loadings for the discriminant functions.

View larger version (30K): [in a new window]   Fig. 10. Anterior views of the position of the hip (black inverted triangles), knee (red circles), ankle (yellow squares), metatarsal (green triangles), and toe tip (blue diamonds) for a single C. calyptratus moving on a level perch (A) and a level treadmill (B), and a single D. dorsalis moving on a level treadmill (C). Each panel is a composite of four strides, with approximately 25 points per stride. The mean position traveled by the mid-dorsal line was standardized to z=0.

View larger version (14K): [in a new window]   Fig. 11. (A) Discriminant function 1 (DF1) versus discriminant function 2 (DF2) and (B) DF1 versus discriminant function 3 (DF3), from an analysis of 16 kinematic variables for D. dorsalis (filled symbols) and C. calyptratus (open symbols) moving on a treadmill. Each point is for an individual stride. Table 6 provides the canonical loadings for the discriminant functions.